One-time purchase or subscription? What should I choose?

The advantage of a subscription is that the Premium license is renewed automatically and for an unlimited amount of time. As a result:
- you don't have to make purchases manually every time your Premium access expires,
- you don't have to worry about loosing Premium access (subscription is secured against such situations).

The advantage of the one-time payment option is the simplicity of this form of purchase. You make a purchase for a defined period of time (from 1 to 24 months) by means of known payment methods (in the event that you have not used Google Play or the App Store for purchasing a subscription, such a payment method might cause concern, e.g. in terms of transaction security).